This application is an improvement upon the disclosure of application Ser. No. 565,733, filed Apr. 7, 1975 for "Molten Adhesive Dispensing Device", which application is assigned to the assignee of this application.
This invention relates to the application of liquids to surfaces and especially to equipment used to apply beads, ribbons or small unitary deposits of extruded or sprayed material in a desired pattern under high speed production conditions. More particularly, the invention relates to equipment which is particularly suitable for applying heated liquids such as "hot melt" molten adhesives to various materials such as flat sheet or webs of paper or cardboard of the type commonly used in packaging a variety of products. The invention, is equally applicable to the application of other liquid materials such as coating materials and paint which may be applied cold or at room temperature.
"Hot melt" liquids are typically of the synthetic resin type and are generally in their solid state at room temperature. When heated to molten form, they change in physical state to a relatively viscous liquid which may be pumped through the nozzle of an applicator tool or gun and applied to a surface in the form of a continuous bead or ribbon or as intermittent deposits. Normally, the molten feed stock is transmitted from solid state (e.g., pellets, bulk, billet or chunk) to molten state at a separate location by a melter structure separate from the adhesive dispenser itself. The molten feed stock is then pumped from the melter structure to the adhesive dispenser through the adhesive feed hose connected to the dispenser. Independent supply systems for melting and forwarding thermoplastic adhesive material through a feed hose to a separate adhesive dispenser or hand operated gun structure are illustrated in U.S. Pat. No. 3,964,645 for "Apparatus for Melting and Dispensing Thermoplastic Material", issued June 22, 1976 and assigned to the assignee of this application.